• Journal of the Korea institute for structural maintenance and inspection
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• v.21 no.4
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• pp.80-86
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• 2017

The purpose of this study is to construct a pattern database of pipes and cavities buried in the ground to prevent ground subsidence. To do this, it developed a pattern template algorithm using Open CV and applied it to the results of GPR detection results of tank. As a result, proper pattern database construction was possible. Since the results of this study are based only on limited experimental results, it is expected that more realistic data will be constructed if various field data and detection results of large test beds are supplemented in the future.

• Journal of the Korea institute for structural maintenance and inspection
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• v.22 no.3
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• pp.46-52
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• 2018

Detail development and performance tests were conducted for the purpose of developing a damper system capable of lateral displacement control of existing frame structures. The development details are 1) ALD designed to prevent deformation of beams between columns and 2) AWD designed to control inter-story displacement. The non-reinforced BF specimen was used as a comparative study. The evaluation variables are failure mode, load-displacement curve, envelope curve, maximum strength, stiffness degradation and energy dissipation capacity. As a result, the seismic strengthening effect of ALD and AWD was confirmed. Also, it was confirmed that the method of restraining the column with the aramid sheet is superior to the improvement of the seismic performance.

• Journal of the Korea institute for structural maintenance and inspection
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• v.7 no.1
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• pp.157-163
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• 2003

Recently, the number of Prestressed Concrete(PSC) bridges needed repair and retrofit because of the increase of heavy traffic loads and aging of concrete materials. But there are a few related researches about strengthening PSC bridges. In this study, the practicability of strengthening methods for PSC beam were studied by the static experimental method. PSC beams in length of 6m were made with concrete slabs. Glass fiber sheeting and external post-tensioning methods were used for strengthening PSC beams. Some beams were strengthened after cracks to investigate the applicability for cracked bridges. As a result, there strengthening methods were efficient at increasing the cracking loads and the failure load, to decrease deflection and prevent cracks. In the case of using glass fiber retrofit methods, it should be careful in the anchorage problems for preventing the bonding failure.

• Journal of the Korea institute for structural maintenance and inspection
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• v.18 no.4
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• pp.84-91
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• 2014

In this study, in order to find the improvement effect of metakaolin for using improvement of strength in concrete structures, it is investigated the diffusion coefficient of chloride ions and adiabatic temperature rise test. As a result, due to the mixing of metakaolin, it has been confirmed reducing diffusion coefficient of chloride ions and could prevent down of slump for use of adding fly ash. Therefore, ensuring resistance to chloride ion penetration into concrete, it is possible to enlarge the W/B ratio and reduce the adiabatic temperature rise by mixing of metakaolin. So, it is confirmed that the durability of concrete structures is increased.

• The Journal of the Korean dental association
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• v.55 no.1
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• pp.22-29
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• 2017

Purpose : Preservation of the periodontal health of the treated patient requires supportive periodontal therapy for the elimination of periodontal disease. After Phase I therapy is completed, patients are placed on a schedule of periodic recall visits for maintenance care to prevent recurrence of the disease. The amount of tooth loss would be the most relevant criterion in an evaluation of the effect of periodontal treatment, but this would require studies with extremely long follow-up periods. Thus the most commonly used outcome criteria in clinical research have been clinical attachment level change, reduction of pocket depth and bleeding frequency. The purpose of this case study is to identify the effect of supportive periodontal therapy after periodontal flap surgery. Materials & Methods : Following routine hygienic phase of treatment, patients with chronic periodontitis received surgical periodontal treatment. Bleeding on probing, pocket depth and clinical attachment level were measured at baseline, pre-operation and 1 year follow up. All procedures were performed by one operator. Results : One year a total of 28 patients (58sites) to recheck remained, when conducted maintenance program after periodontal flap surgery was observed reduction of bleeding frequency, pocket depth and improvement of clinical attachment level. Conclusion : The results from this study indicate that supportive periodontal therapy after periodontal flap surgery is effective for reduction of bleeding frequency, pocket depth and gain of clinical attachment level.

• Journal of the Korea institute for structural maintenance and inspection
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• v.5 no.2
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• pp.147-154
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• 2001

The prestressed concrete containment is one of the most important structures in nuclear power plants, which is required to prevent release of radioactive or hazardous effluents to the environment even in the case of a severe accident. Numerical analyses are carried out by using the ABAQUS finite element program to assess the ultimate pressure capacity of the Y prestressed concrete containment with light water reactor at design criteria condition and aging condition considering varied properties of time-dependant materials respectively. From the results, it is verified that the structural capacity of the Y prestressed concrete containment building under the present, aging condition is still robust. In addition, the parameter studies for the reduction of the ultimate pressure capacity of containment building according to the degradation levels of the main structural materials are carried out. The results show that when the degradations of each materials are considered as individual and combined forms, the influence is large in the order of tendon, rebar and concrete degradation, and tendon-rebar, tendon-concrete and rebar-concrete degradation respectively.

• Journal of the Korea institute for structural maintenance and inspection
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• v.6 no.2
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• pp.175-182
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• 2002

The cement injection technology on the purpose of ground reinforcement and cut-off has been used in construction sites until now. However, recently it is applied to prevent leakage of underground structure. In this study, applicability of the back side waterproof grouting method was verified through performing field model tests and reviewing case histories. From the results of this study, injection shape of the back side waterproof grouting method was appeared to be root type, and waterproof effect by injection of cement grout material was excellent because grout material infiltrated into boundary between wall of structure and back side ground to be waterproof layer. Components influencing infiltration of injection material are type of soil and degree of compaction. For effective injection, injection pressure has to vary gradually from high pressure to low pessure and small quantity of injection material has to be injected for long times. Also, spacing of injection hole must be designed considering condition of back side ground, injection area, W/C ratio, the number of injection and injection pattern properly.

• IEMEK Journal of Embedded Systems and Applications
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• v.9 no.3
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• pp.127-135
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• 2014

On lot of ships, Ballast Water Treatment Systems(BWTS) are in use, or the newly built ship should be mandatory installation by 2017. It is IMO(International Maritime Organization) regulations. Because the vessel is in long distance, It is managed this system only in the vessel and it may occur considerable cost of maintenance when a problem arises from BWTS. We describe in this paper how to monitor treated ballast water to make sure the ballast water and BWTS on a ship is in proper condition, but before the port entrance. In addition, analysing and forecasting trend signal to prevent failure. Also we can expect reduce the cost of BWTS maintenance. We can monitor the sensor data value's change which collected through satellite from BWTS. And we can observate the ballasting and de-ballasting state of the vessel easily.

• KIPS Transactions on Software and Data Engineering
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• v.5 no.3
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• pp.117-124
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• 2016

The demands for additional functionalities and improvements in performance of software increase over time. In particular, increases in software complexity and requirements for quality control attributed to continued maintenance lead to the deterioration of software quality and raises in software life cycle costs. In order to prevent this, software operators have to conduct timely redevelopment of the software. However, the scope of previous studies on timely redevelopment of software is limited to enterprises. We, in this study, suggest a model to derive the optimal cycle for the redevelopment of governmental agency software using Renewal process and discuss its correlation with previous studies.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.33 no.3
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• pp.239-244
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• 2020

This study examines the feasibility of the image deep learning method using convolution neural networks (CNNs) to maintain a porcelain insulator. Data augmentation is performed to prevent over-fitting, and the classification performance is evaluated by training the age, material, region, and pollution level of the insulator using image data in which the background and labelling are removed. Based on the results, it was difficult to predict the age, but it was possible to classify 76% of the materials, 60% of the pollution level, and more than 90% of the regions. From the results of this study, we identified the potential and limitations of the CNN classification for the four groups currently classified. However, it was possible to detect discoloration of the porcelain insulator resulting from physical, chemical, and climatic factors. Based on this, it will be possible to estimate the corrosion of the cap and discoloration of the porcelain caused by environmental deterioration, abnormal voltage, and lightning.